Colored light system



May 15, 1962 w. E. GLENN COLORED LIGHT SYSTEM Original Fi led June 1,1954 2 Sheets-Sheet 1 Fig.

m M R R R in ventor: VVi/fiam E. Glenn,

55; 68554! GLUE 05 C. 0 SC. as C. I 4/ 42 Hi; A ttorney.

2 Sheets-Sheet 2 Original Filed June 1, 1954 Inventor: VVi/lidm E.G/enn, by 14 M His Attorney.

United States Patent Ofiiice Re. 25,169 Reissued May 15, 1962 25,169COLORED LIGHT SYSTEM William E. Glenn, Scotia, N.Y., assignor to GeneralElectric Company, a corporation of New York Original No. 2,813,146,dated Nov. 12, 1957, Ser. No.

433,448, June 1, 1954. Application for reissue Oct.

28, 1959, Ser. No. 849,422

20 Claims. (Cl. 178-54) Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

This invention relates to an apparatus and method for producing andprojecting colored light images in accordance with a color intelligencesignal.

While this invention is subject to a wide range of applications, it isespecially suited for use in a color television system and isparticularly described in that connection.

Apparatus and methods are known for projecting black and while lightimages on a screen and for pro jecting television images on a screen. Aform of television projection system may consist of a light modulatingmedium which is used as a light valve. A system of bars defining asystem of slits is placed between a source of light and the medium. Asecond system of bars and slits is placed between the medium and aprojection screen. When no signal is applied to the medium the lightpassing through the first system of slits falls directly on the bars ofthe second system of bars and slits and when the medium is modulated byan electron stream the light is deflected sufficiently to pass throughthe slits. The amount of light passed is determined by the amount themedium is modulated by the video signal. In this manner, an enlargedtelevision image may be produced on a screen. The width of the slits isgreat enough so that all color components that are diffracted by themedium are passed, thereby resulting in a black and white image.

This system has the advantage of permitting the use of an intense sourceof light such as an arc lamp, and controlling the intensity of lightprojected on a screen by a video signal. It is noted that the modulatingmedium may be applied to the face of a mirror to control the directionof reflected light. Previously known systems, of the general typedescribed, have been used to project sequential color information buthave not been capable of projecting simultaneous color information on ascreen by the use of a single light modulating medium.

It is an object of this invention to provide a method and apparatus forprojecting a colored light image.

Another object of this invention is to provide an apparatus and methodfor controlling the relative intensities of the color components from asource of white light.

A further object of this invention is to provide an apparatus and methodfor reproducing simultaneous color television pictures.

This invention provides an apparatus and method for controlling theintensity and color of light projected-by a light projection system.This apparatus, in a preferred embodiment, comprises a light modulatingmedium, the light modulating characteristics of which are controlled inaccordance with color intelligence signals by applying the signal to themedium.

A better understanding of this invention may be had by referring to thefigures of the drawing in which Figures 1 through 3 are illustrative ofwell known optical principles; Figure 4 is a semi-schematic diagram of asystem in accordance with this invention; Figure 5 illustrates a featureof the system illustrated in Figure 4, Figure 6 is an illustration of aspecific embodiment of this invention, and Figure 7 illustrates a secondembodiment of this invention.

A diffraction grating is a light transmitting or reflecting medium whichbreaks up a ray of impinging monochromatic light into a series of lightand dark banks or white light into colored bands of the spectrum oflight present in the ray. White light is generally considered to be butis not necessarily limited to light made up of all color components inthe visible spectrum which may be considered to be light withwavelengths ranging from approximately 4000 to 8000 angstrorn units.Light of a single component color having a single wavelength only, isgenerally defined as monochromatic light.

A diffraction grating may be formed by distorting the surface of amedium so that light projected through or reflected from this medium isdiffracted into its component colors. The respective color componentsfollow paths which deviate from a line normal to the effective plane ofthe medium by an amount which is a function of the wavelength of theparticular color component. This invention, according to a preferredembodiment, utilizes a system of bars and slits which are so orientedwith respect to the medium that the wavelength of the light that ispassed by the slit system is controlled by the modulating medium. Threediffraction gratings are effectively superimposed on the modulatingmedium to form a single composite grating so that a color image ispassed by the system of slits which corresponds to the colorintelligence applied to distort the modulating medium.

Figure 1 illustrates basic optical principles reviewed herein as an aidto understanding of a specific embodiment of this invention. Figure 1shows a light source 16, an elementary diffraction grating 11, a plane12, a representation of the distribution of monochromatic light 13, arepresentation of the distribution of color components of diffractedwhite light 14 and a slit system 15. The slits illustrated in grating 11are separated by a distance d, of the order of a wavelength of light,and may be considered to form a small part only of a grating.

For the purposes of this discussion it is assumed that the light fromsource 10 comes from a sufficient distance so that a plane wave falls ongrating 11. The light arrives at the left hand surface of diffractiongrating 11 in the same phase at all points on the surface. It is wellknown that light may be considered to be formed of a series of rayswhich travel outwardly from any given point. Therefore, all lightpassing through the slits in grating 11 does not travel in the samedirection. Portions of this light are separated or diffracted asillustrated by the lines extending from the slits in grating 11 to thescreen 12. A portion of the light passing through the slit 17 strikesregion B on screen 12 and a portion of this light strikes region F.Light from slit 18 in diffraction grating 11 in part strikes region Gand other portions strike F in phase with the light from slit 17 so thatlight is observed at region F. The light arriving at G from slit 17 isout of phase with light from slit 18 so that'no light is observed atregion G. The light does not form areas of absolute dark and light butforms regions varying in light intensity from absolute black to light.

It is noted that the preceding discussion in regard to Figure 1 has beenlimited to that case where the light source 10 consists of monochromaticlight. It is apparent from the distribution of light illustrated inregion 13 that there are successive regions of light and dark. Theselight regions are designated by L L and L and the dark regions by D andD That region in which the light is not diffracted as designated by thereference L and is called the zero order diffraction pattern. This zeroorder diffraction pattern has a finite width as illustrated by theshaded area. The next area designated by D -L is generally defined asthe first order diffraction pattern. The light from slit 17 falling inthis region. which is centered about the point P on screen 12 has beendelayed one wavelength with respect to the light from slit 1%. In a likemanner, D and L designate the dark and light regions of the second orderdiffraction pattern in which light from slit 17 is delayed twowavelengths before reaching the screen 12, light from slit 18 is delayedone wavelength, both with respect to a third slit designated as r19.

The relationship between the slit distance d in the diffraction grating11 and the distance between the Zero and first order diffractionpatterns yields a well known equation. This equation is written %=sin a,1

where x is the wavelength of the light under consideration, d is thegrating spacing and 0,, is the angle formed between a line from the norder diffraction pattern to the grating with respect to a line'from,vthe zero order defraction pattern to the grating.

It is apparent fromv Equation 1 that thedefinition of the light and darkareas, which may be termed the resolution of grating 11, is increased asthe spacing between the slits or grating is decreased thereby resultingin an increased number of slits per unit area.

It is also apparent from Equation 1 that, for a given grating spacing,the angle will vary with the wavelength of the light applied to thediffraction grating. If the monochromatic light source is replaced by asource of White light a spectral array of colors results. The shorterwavelengths are diffracted least from the zero order direction and thelonger wavelengths such as the red colors are diffracted the greatestamount. The first, second and third order color distribution isrepresented on plane 14. It will be noted that there is an overlappingof the second and third order diffraction patterns. Therefore, with theillustrated diffraction grating a complete spectrum of pure spectralcolors is obtained in the first order diffraction pattern only.

Screen 15 may be considered to be provided with a slit 16 which is ofsufiicient width and is properly oriented to pass only a selected colorfrom the first order diffraction pattern. Therefore, only those colorcomponents from source 10 which are in register with the slit 16 inscreen 15 are passed by the screen. The remainder of the light impingeson the optically opaque portion of screen 15. If the distance d betweenthe grating lines is changed, a different color is passed by screen 15.Therefore, the color of the light passed by the screen 15 may becontrolled by varying the grating spacing.

The system of the present invention uses in place of the fixed parameteror static diffraction grating Id of Fig. l a superimposed or compositegrating of the phase grating type with each component of the gratingcorresponding to a component color. Color intelligence signals are usedto control the intensity of the light passed by each of the threegratings in accordance with three spectral color components which may becombined to produce any color light or white light. For example, theintensity of light passed by one of the gratings is controlled by asignal representative of blue light, the intensity of light passed by asecond grating by a signal representative of green light, andtheintensity of light The slit 16 in screen 15 is oriented to pass blue,

through this glass or film or the glass or film may be provided with asilvered reflecting surface on the back thereof so that light passesthrough the difiraction grating in two directions. The ability of thistype of grating to control the intensity of light passing through thegrating is limited as is the ability to control the light intensity ofthe colors in any one order diffraction pattern. Therefore, it isnecessary to resort to a type of diffraction grating which may be usedto control the intensity of light. By way of example, a preferredembodiment of this invention uses a grating generally referred to as aphase grating which controls the color distribution and intensity in thediifraction pattern.

A portion of a phase grating is illustrated in Figure 2 of the drawing.Light may be passed through this grating or a light reflecting layer maybe applied to the front surface 20 or back surface 21 of the grating sothat light may be reflected from surface 20 or surface 21. The surface20 forms a sine wave distortion on the medium forming the grating sothat light applied to the grating is shifted in phase in accordance witha sine function of the distance d along the grating; therefore, thegratingof Figure 2 is generally defined a sine function phase grating.It is noted that diffraction and intensity control effects can beobtained with other grating configurations. The essential feature isthat there be provided a light modulating medium the light modulatingeifects of which can be controlled by an external signal source. Thespecific embodiment of this invention Which is described, utilizes asine function phase grating; however, this invention may be carried outby utilizing diffraction gratings having other configurations.

Figure 3 illustrates a plot of the Bessel function squared of lightintensity as a function of the grating amplitude x in a sine functionphase grating for the zero order diffraction pattern at (l the firstorder diffraction pattern at (I9 and the second order diffractionpattern at (1 It may be shown that the light intensity of monochromaticlight varies as the square of the Bessel function of the gratingamplitude x. Figure 2 shows the Wavelength of the sine function phasegrating as the dimension d which is the substantial equivalent of thedimension d in Figure 1. Equation 1 also expresses the relation betweendimension d, the light Wavelength and the angle subtended by the firstorder diffraction pattern of the sine function phase grating illustratedin Figure 2.

The maximum intensity of monochromatic light in the first orderdiffraction pattern occurs when the distance x from peak to trough ofthe sine function grating is such that a phase difference of one-halfwavelength exists between light emanating from a trough and from a peakof the phase grating. This invention utilizes light in the first orderdiffraction pattern only. The slits in a screen, such as slit 16 inscreen 15 of Figure l, are of such width as to pass the first orderdiffraction pattern and some second order diffraction pattern fromadjacent slits in grating 11. The second order diffraction intensity islow enough relative to the first order diffraction intensity so that theeye detects colors from the first order diffraction pattern only;therefore, a preferred embodiment of this invention is said to utilizethe first order diffraction pattern colors.

In view of the foregoing, it is apparent that the intensity and color oflight passed may be controlled by a phase grating and slit system. Agiven component of a color picture may be considered to be made up of amixture of colored light. These light colors may be selected in anyconvenient fashion. For the purpose of the explanation in thisspecification one particular color grouping is selected although it willbe clearly understood by those skilled in the art that any system ofcolor coordinates may be selected to operate in the apparatus of thisinvention.

It is considered that any given color may be composed of a mixture of apure blue light, a pure green light and a pure red light. Screen isprovided with a plurality of slits of such width and spacing relative tothe modulating medium that only first order diffraction components arepassed, whereby a color picture may be obtained from a white lightsource.

According to an embodiment of this invention a given color is projectedby passing white light through a phase grating with wavelength dselected to pass red light, a second phase grating with a wavelength dto pass green light and a third phase grating with a wavelength d topass red light. The respective amplitudes of the red, green and bluecomponents are controlled by varying the amplitude of the peak to thetrough distance x of the respective phase gratings. The light passed byeach of these gratings is passed through a slit and bar system such asscreen 15 to obtain the given colored light.

In a preferred embodiment the sine function components representative ofthe wavelengths and intensities of the three color components areinstantaneously combined to obtain a composite phase grating wave formwhich results in the desired color being passed by the output bar andslit system which corresponds to the screen 15 of Fig. l. The sum ofthree television color signals are combined to simultaneously modulatethe scanning velocity of an electron stream which is applied to themodulatnig medium and results in a composite diffraction phase gratingequivalent to three superimposed phase gratings so that the desiredcolor is transmitted through the output bar and slit system.

An approximate equation may be written for the intensity of the firstorder color signal, for example, a red signal in a composite phasegrating, and appears as This relation indicates that the intensity ofthe red signal is approximately equal to the square of the first orderBessel function of the red signal times a factor consisting of theproduct of the zero order Bessel function of the blue signal and thezero order Bessel function of the green signal. This equation relatesthe effective cross-modulation of the colors. It may be shown that forlow phase grating amplitudes, the zero order Bessel function product issubstantially unity so that the squared first order Bessel function forthe red component is a reasonably good representation of the intensityof the transmitted red signal.

Figure 4 illustrates an example of an application of this invention to alight transmission system for projecting a color television image on ascreen. There is shown a source of light 22, a first bar system 23, alens system 24, a light modulating medium 25, a lens system 26, a barsystem 27, a projection lens system 28 and a screen 29. A portion of avideo system 30 provides an electron stream for deforming modulatingmedium 25.

The modulating medium is deformed by the electron stream from the videosystem 30. Light from source 22 is projected on bar system 23 whichconsists of a system of bars separated by slits. When the modulatingmedium 25 is not deformed by the electron stream, the lens system 24 and26 project the image of the slits in bar system 23 onto the bars of thebar system 27 so that no light from source 22 passes through lens system28 to the projection screen 29. When the modulating me dium 25 isdistorted by the electron stream in accordance with color video signals,the light from source 22 passes through the slits of bar system 23 andis diffracted so that it passes through the slits in system 27 and isprojected on the screen 29.

The light modulating medium distorting system comprises mixer tubes 31,32 and 33 into which are fed the outputs of a source of red videosignals 37, a source of green video signals 38 and a source of bluevideo signals 39. These three signal sources provide the amplitudesignal for the light modulating coating 25 on plate 36.

6 The system utilizes three oscillators 40, 41 and 42 which provideseparate fixed frequency signals for each of the respective colors. Forexample, the red oscillator provides a 14 megacycle signal, the greenoscillator provides a 17 megacycle signal and the blue oscillatorprovides a 20 megacycle signal.

The respective red video signal and red oscillator signal are mixed inconverter 31. The green and blue video signals are mixed with therespective color controlling oscillator signals in converters 32 and 33respectively. The resulting output of the converters 31, 32 and 33 is a14 megacycle, 17 megacycle and 20 megacycle signal respectively theamplitudes of which are controlled by the video signal input for therespective colors. The combined output of tubes 31, 32 and 33 is appliedto the electrostatic deflection plates 34 of the illustrated electrongun. The output of the electron gun is swept across the modulatingcoating in a conventional manner by magnetic deflection coils 35 whichare fed by video sweep source 43 to form an interlace sweep trace. It isnoted, that as an alternative, a signal mixing system may be used inwhich each of tubes 31, 32 and 33 serves as an oscillator and as amixer.

The resulting signals which are applied to electrostatic deflectionplates 34 cause a variation in the sweep rate at the frequency ofoscillation for the given color. The amplitudes of the color videosignals determine the peak to trough distance in the resulting phasegrating and thereby the relative intensities of the colors projected foreach picture element, and z he luminance of the picture. The threecolors are combined as illustrated so that an element-by-elementsimultaneous color picture is obtained. That is, the resulting phasegrating produces upon the slit system 27 an interference spectra suchthat only light of predetermined dominant wave lengths is passed, thesewave lengths being related to the colors of which the voltage waves fromsources 40, 41, and 42 are representative. It is noted that a completecolor television receiving system is not shown since this invention maybe adapted to a variety of conventional color television systems. Inorder to obtain satisfactory color and picture resolution, a particularembodiment of my invention utilizes approximately 10 grating lines perpicture element.

Any satisfactory source of light may be used, for example, the source oflight 22 may consist of an arc lamp or a conventional projection lampwhich is fed through a lens condensing system so that an image of thefilament or of the arc is projected on the slits of bar system 23. Thebar system 23 may consist of a transparent material such as glass withoptically opaque bars painted thereon or as an alternative a sheet ofnon-magnetic material with milled slits may be used. The centerto-centerspacing between the slits in the bar system 23 is 50 mils and the widthof the slits is 10 mils. The spacing of the bars and slits in the barsystem 23, as well as the spacing of the bar system in the over-alloptical system, is determined by application of well known opticalrelations.

Bar system 27 consists of 18 mil slits with a 50 mil center-to-centerspacing. It may be shown that the intensity of light on the screen isapproximately proportional to the product of the width of the slits inbar system 23 times the width of the slits in bar system 27 so that theintensity is a maximum, for a given color resolution or band of colorspassed, when the width of the slits in bar system 23 and 27 are equal.With the lens system utilized, better picture element resolution isrealized, without appreciably reducing the efliciency, by making theslits in the second bar system wider than the slits in the first barsystem to counteract the difiracting effects of the second bar and slitsystem 27.

Figure 5 illustrates schematically the bar and slit system utilized in apreferred embodiment of this invention. The slits are spaced inaccordance with well known optical principles to provide for overlappingdifiraction patterns.

It is assumed, for purposes of this discussion, that the modulatingmedium 25 is distorted so that green light only will be passed by thebar system 27. The solid lines represent the paths followed by light inthe zero order diffraction pattern and the dashed lines represent thegreen light in the first order diffraction pattern. The zero order andfirst order diffraction pattern green light is labeled for the lightcoming from a pair of slits in a bar system, such as 23 in Figure 4,which is dilfraclted by a single point of modulating medium 25. Anadditional slit is provided on each side of the zero order pattern andbetween the zero order and first order patterns. These slits pass firstorder light form adjacent slits. By utilizing a bar system withoverlapping diffraction patterns as shown in Figure a gain in lightoutput by a factor of three is obtained over ba systems which do notutilize bar systems with overlapping diffraction patterns.

The light modulating medium 25 illustrated in Figure 4 may be made ofany material, the light phase shifting characteristics of which may bealtered by an external stimulus to which color intelligence may beadded. The external stimulus may take the form of an electron beam,heat, sound, or any other form of energy which varies the phase shiftingcharacteristics of the modulating medium. As an example of one type ofmodulating medium, there is illustrated in Figure 4 a transparent member36 and a gelatinous layer which is the modulating medium 25. To formthis modulating medium a conductive gelatinous coating, approximately 3mils thick, is placed on the surface of the transparent member 36.

In this embodiment the laye used as a modulating medium is distorted bybeing struck with electrons which build up temporary charges on onesurface of the layer. The charged portions of the surface are attractedto the opposing surface thereby forming valleys or dips in thegelatinous layer.

In the system illustrated in Figure 4, gelatinous layer 25 ontransparent plate 36 must be easily distorted. If the layer is too thickthe distance between the charge placed by the electron stream on thesurface of gelatinous layer 25 and the surface of 36 will be too greatand the medium will not be easily deformed. If the layer is too thin,there will be too little material to be squeezed out between the topsurface of the layer and the surface of 36 so that it will be ditficultto obtain sufficient grating amplitude on the layer.

It is also necessary that the modulating medium withstand bombardment byan electron stream without the properties thereof changing. The timeconstant at which charges leak ofi? must be such that the gelatinousmaterial resumes its original shape before the next color intelligencesignal is projected on to a given area of the modulating medium;however, as a matter of practical design it is sometimes necessary toeffect a compromise between persistence and light intensity therebyresulting in a one or two frame 'holdover of deformation for highintensity picture elements.

It is noted that the source of electrons which modulate the diffractioncoating may take any number of forms and that the illustrated circuitsis given merely by way of example and is not intended to be limiting.Other methods may be devised for applying the color intelligence to amodulating coating so as to vary the light modulating characteristicsthereof and result in a color image. For example, this invention may beeasily adapted for use with conventional single side band systems inwhich color intelligence in a form other than signals representative ofpure spectral colors is carried on separate side bands along with theblack and white video signal.

This system can also be utilized to project a black and white picture.For example, this may be accomplished by feeding a fixed signal from thered, green and blue video sources onto the plates so as to obtain ablack and white signal. The relative strengths of the red, green andblue video sources remain constant, however, the total amplitude outputvaries in accordance with the intensity of the picture elements of theblack and white signal. This invention can be adapted for use with fieldsequential color system by sequentially distorting the medium 25 with amodulating signal representative of each of the component colors.

It will be readily appreciated that the systems of Figure 4 may bereadily adapted to a reflecting system such as that illustrated inFigure 6 which shows another embodiment of this invention utilizing areflecting wave system which is essentially the same as the system ofFigure 4 except that the modulating coating has been placed on aspherical mirror 44. The system consists of an electron gun 45,electrostatic color signal deflecting plates 46, focusing anode 47,prisms 48 and 49, bar and slit system 5t) and 51, magnetic scanningcoils 52, coated spherical mirror 44, light source 53, projection lens54 and viewing screen 55. A source of color signals 57 is coupled todeflecting plates 46. A portion of the system may be enclosed in anevacuated envelope having .a configuration such as that illustrated bythe dashed outline v58.

Light from source 53 is projected on prism 49 and is reflected downwardthrough bar system 51 to the surface of gel coated spherical mirror 44.If no signal is applied to the gel coated mirror the light reflected bythe .mirror strikes the opaque bars in the bar system 50 which is placedon the bottom of prism 48. When a properly modulated electron stream isprojected along the axis of mirror 44 through the hole 56, between theprisms 48 and 49, and on to the gel coated spherical mirror 44, thelight from source 53 is dilfracted so as to pass through the slits inbar system 50 and be reflected by prism 48 so as to pass throughprojection lens 54 on to screen 55 thereby resulting in a color image.The scanning coils 52 cause the electron stream to sweep mirror 44 andare placed below prisms 48 and 49 so that the electron gun may beoriented on the mirror axis.

It is noted that reference numerals 50 and 51, used to designate the barsystem in Figure 6, are considered to be the equivalent of the barsystems 23 and 27 illustrated in Figure 4 of the drawing. The mirror maybe coated with any satisfactory modulating medium such as a silicone oilor a gelatinous form of silicone oil. It is noted that the signalapplied to plates 46 by source 57 may consist of a signal such as thatproduced by the system 3i? which is schematically illustrated in Figure4.

Figure 7 illustrates an embodiment of this invention which consists inthe utilization of black and white photographic film to produce acolored light or picture image. This is accomplished by preparing threebar and slit systems 61, 63 and 64. Bar system 61 is formed by placingstrips of red light absorbent material 62 on a sheet of clear film. Thestrips of red light absorbent material having a center to center spacingequal to the width of the slits in an equivalent diffraction gratingthat would pass red light only when placed in the position of lightmodulating medium 25 in the system illustrated in Figure 4. Bar system63 and 64, with strips of green and blue absorptive materialrespectively, are prepared in a similar manner have the same spacingrelative to the red strips as the green and blue wave lengths haverespectively relative to the red wave length.

The three systems 61, 63 and 64 are superimposed on a sensitized blackand White photographic plate or film 65 and a picture of .a coloredobject is photographed, the colored light acting as the colorintelligence signal. The photographic plate is developed and substitutedfor modulating medium 2.5 in a system such as that illustrated in Figure4. When light from source [41} 22 is projected through the systemincluding the exposed photographic plate a colored light image of thephotographic object results.

This will be more apparent when the effect of bar System61 on thephotographic film is considered alone. If it is assumed that red lightonly is projected on the photographic plate or film, it is then apparentthat the areas between strips [42] .62 will be exposed and opticallyopaque when the film is developed. The film which was under the stripstransmits light, and the plate or film acts as an intensity d-itfractiongrating of such spacing that red light only is projected on screen 29when the film is substituted for modulating medium 25.

It will be apparent to those skilled in the art that this inventionprovides a method and apparatus for producing color images in accordancewith an applied color intelligence signal. The embodiments specificallydescribed and illustrated herein are given merely by way of example andare not to be considered limiting since this invention may take a widevariety of forms.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A system for presenting color information on a light modulatingmedium corresponding to a display comprising a unitary light modulatingmedium, and means simultaneously subjecting said light modulating mediumto color intelligence signals having different values of one parametercorresponding to dilferent color components in the display and a secondparameter varying in accordance with the intensity of each of saiddifferent color components, said means including electrical means forproviding an arrangement of electrical charge on a surface of said lightmodulating medium under the control of said color intelligence signalsto establish simultaneously diffraction patterns on said medium witheach pattern having a parameter corresponding to a diiferent one of saidcomponents and a second parameter varying pointby-point with theintensity of said one of said components.

2. A system for presenting color information on a light modulationmedium corresponding to a display comprising a unitary light modulatingmedium, and means simultaneously subjecting said light modulating mediumto color intelligence signals having difierent values of one parametercorresponding to different color components in the display and a secondparameter varying in accordance with the intensity of each of saiddifferent color components, said means including electrical means forproviding an arrangement of electrical charge on a surface of said lightmodulating medium under the control of 7 said color intelligence signalsto deform said medium and establish simultaneously phase difiractionpatterns on said medium with each of said patterns having a wave lengthcorresponding to a difierent one of said color components and anamplitude varying point-by-point with the intensity of said one of saidcomponents.

3. A system for producing a color image corresponding to a displaycomprising a unitary light modulating medium, means simultaneouslysubjecting said light modulating medium to color intelligence signalshaving different values of one parameter corresponding to diiferentcolor components in the display and a second parameter varying inaccordance with the intensity of each of said difierent colorcomponents, said means including electrical means for providing anarrangement of electrical charge on a surface of said light modulatingmedium under the control of said color intelligence signals to establishsimultaneously diffraction patterns on said medium with each patternhaving a parameter corresponding to a different one of said componentsand a second parameter varying point-by-point with the intensity of saidone of said components, and a source of light for illuminating saidmedium with substantially parallel light rays and means including alight mask for blocking zero order light diffraction patterns emanatingfrom said medium and passing first order light dilfraction patternsemanating from said medium to produce an image having point-by-pointcolor and intensity correspondence with the display.

4. A system for producing a color image corresponding to a displaycomprising a unitary light modulating medium, means simultaneouslysubjecting said light modulating medium to color intelligence signalshaving dilferent values of one parameter corresponding to difierentcolor components in the display and a second parameter varying inaccordance with the intensity of each of said difierent colorcomponents, said means including electrical means for providing anarrangement of electrical charge on a surface of said light modulatingmedium under the control of said color intelligence signals to deformsaid medium and establish simultaneously phase dilfraction patterns onsaid medium with each of said patterns having a wave lengthcorresponding to a different one of said color components and anamplitude varying point-by-point with the intensity of said one of saidcomponents, and a source of light for illuminating said medium withsubstantially parallel light rays and means including a light mask forblocking zero order light diffraction patterns emanating from saidmedium and passing first order light diffraction patterns emanating fromsaid medium to produce an image having point-by-point color andintensity correspondence with the display.

5. A system for producing a color image corresponding to a displaycomprising a unitary light modulating me dium, means providingelectrical color intelligence signals having difierent values of oneparameter in accord with color components of said display and a secondparameter varying in accordance with the intensities of said components,means producing an electron beam and scanning it over a surface of saidlight modulating medium, means controlling said beam by said electricalcolor intelligence signals to establish superimposed diifractionpatterns on said medium with each pattern having a parametercorresponding to one of said color components and a second parametervarying point-by-point with the intensity of said one of saidcomponents, a source of light for illuminating said medium withsubstantially parallel light rays and means including a light mask forblocking zero order light difiraction patterns emanating from saidmedium and passing first order light diifraction patterns emanating fromsaid medium to produce an image having pointby-point color and intensitycorrespondence with the display.

6. A system for producing a color image corresponding to a displaycomprising a unitary light modulating medium, means providing electricalcolor intelligence signals having difierent values of one parameter inaccord with color components of said display and a second parametervarying in accordance with the intensities of said components, meansproducing an electron beam and scanning it over a surface of said lightmodulating medium, means controlling said beam by said electrical colorintelligence signals to deform said medium and establish superimposedphase diffraction patterns on said medium with each of said patternshaving a wave length corresponding to a different one of said colorcomponents and an amplitude varying point-by-point with the intensity ofsaid one of said components, a source of light for illuminating saidmedium with substantially parallel light rays and means including alight mask for blocking zero order light diffraction patterns emanatingfrom said medium and passing first order light difiraction patternsemanating from said medium to produce an image having point-by-pointcolor and intensity correspondence with the display.

7. The method of producing color images corresponding to a display whichcomprises establishing on a light modulating medium elemental areadiflraction gratings each having a first grating parameter providing anangle of light diffraction corresponding to the color of the display inthe corresponding elemental image area and having a second gratingparameter varying with the intensity of the light in the correspondingelemental area of the display by transmitting to a surface of saidmodulating medium an arrangement of electrical charge under the controlof color intelligence signals having one parameter correspondingpoint-by-point with the color of the display and a second parametervarying point-by-point over the area of the display in accordance withthe intensities of the component colors, transmitting to said mediumessentially parallel rays of white light and masking zero order lightdiffraction patterns emanating from the medium and passing first orderlight diffraction patterns emanating from said medium to produce animage having point-by-point color correspondence with said di p ay- 8.In combination, a unitary light modulating medium, means for applying anarralngement of electrical charge to a surface of said medium, a sourceof superimposed color intelligence signals for modulating saidarrangement of electrical charge, a source of light, a first memberdefining a plurality of optically transparent areas separated byoptically opaque areas, said member being oriented between said sourceof light and said medium, a second member defining a plurality ofoptically transparent areas separated by optically opaque areas andoriented so that light from said source can pass through said secondmember when said signals are simultaneously applied to said modulatingmedium.

9. In combination, a unitary light modulating medium, means for applyingan arrangement of electrical charge to a surface of said medium, asource of superimposed color intelligence signals for modulating saidarrangement of electrical charge, a source of light, a first memberdefining a plurality of optically transparent areas separated byoptically opaque areas and oriented between said source of light andsaid medium, a second member defining a plurality of opticallytransparent areas separated by optically opaque areas and oriented sothat color components of light from said source can pass through saidsecond member only when said signals are applied to said modulatingmedium and means for simultaneously applying said signals to saidmedium.

10. In a colored light projecting system a unitary light modulatingmedium means for applying an arrangement of electrical charge to asurface of said medium, a source of superimposed color intelligencesignals for modulating said arrangement of electrical charge, a sourceof light, a first member defining a plurality of optically transparentareas separated by optically opaque areas, said first memher beinglocated between said source of light and said medium, a second memberdefining a plurality of optically transparent areas separated byoptically opaque areas and oriented so that the color components oflight from said source which pass through said second member arecontrolled by said signals applied tothe modulating medium, and meansfor simultaneously applying said signals to said medium.

11. In a color television system including an electron gun for producinga stream of electrons, a unitary visible light modulating medium, meansfor causing said electron stream to strike said medium, a source ofsuperimposed .color intelligence signals, a source of white light, afirst member defining a plurality of optically transparent areasseparated by optically opaque areas oriented between said source oflight and said medium, a second member defining a plurality of opticallytransparent areas separated by optically opaque areas and oriented sothat the color components of light from said source that pass throughsaid second member is controlled by the color intelligence signals, andmeans for applying the color intelligence signals to modulate saidelectron stream to control the color and intensity of the light passingthrough said second member.

12. In a color television system, a unitary visible light modulatingmedium, an electron gun producing a stream of electrons substantiallyperpendicular to a surface of said medium, a source of superimposedcolor intelligence signals, a source of white light, a first memberdefining a plurality of optically transparent areas separated byoptically opaque areas oriented between said source of light and saidmedium, a second member defining a plurality of optically transparentareas separated by optically opaque areas and oriented so that the colorcomponents of light from said source that pass through said secondmember are controlled by the color intelligence signals, and means forapplying the color intelligence signals to modulate said electron streamto control the color and intensity of the light passing through saidsecond member.

13. A system for the display of colored light information in response tosuperimposed color intelligence signals, which system comprises a sourceof light, a unitary light modulating medium receiving light from saidsource, means for applying an arrangement of electrical charge to asurface of said medium, said arrangement of electrical charge beingmodulated by said color intelligence signals, a first member defining aplurality of optically transparent areas separated by optically opaqueareas and oriented between said source and said medium, display meansfor colored light information, a second member defining a plurality ofoptically transparent areas separated by optically opaque areas andoriented between said medium and said display means, said first andsecond members cooperating to block the passage of light from saidsource to said display means in the absence of said signals, and meansfor simultaneously imposing difiraction grating patterns upon saidmedium in response to said signals to display said colored lightinformation.

14. A system for the display of colored light information in response tosuperimposed color intelligence signals, which system comprises a sourceof light, a unitary light modulating medium receiving light from saidsource, a first member defining a plurality of optically transparentareas separated by optically opaque areas and oriented between saidsource and said medium, display means for colored light information, asecond member defining a plurality of optically transparent areasseparated by optically opaque areas and oriented between said medium andsaid display means, said first and second members cooperating to blockthe passage of light from said source to said display means in theabsence of said signals, and deformation means for applying anarrangement of electrical charge to a surface of said light modulatingmedium under the control of said color intelligence signals forsimultaneously imposing phase grating ditfraction patterns upon saidmedium in response to said signals to cause components of light fromsaid source to bedisplayed as said colored light information, saiddeformation means including means to 'vary the amplitude of saidpatterns to control light intensity in said display, and meansestablishing wave length of said patterns to control the colorcomponents in said display.

15. A system for presenting color information on a light modulatingmedium corresponding to a display comprising a unitary light modulatingmedium, means providing electrical color intelligence signals eachhaving different values of one parameter in accordance with dilferentcolor components of said display and a second parameter varying inaccordance with the intensity of each of said different components,means producing an electron beam and scanning it over a surface of saidlight modulating medium, means simultaneously controlling said beam bysaid electrical color intelligence signals to establish superimposeddiffraction patterns on said medium with each pattern having a parametercorresponding to a difierent one of said color components and a secondparameter varying point-by-point with the intensity of said one of saidcomponents.

16. Apparatus for producing color television images by means of a sourceof a plurality of wavelengths of light, an image-bearing medium, meansfor deforming the surface of said medium, first and second slit systems,said medium being located between said first and sec-- and slit systems,said source being adapted to cause said light of said plurality ofwavelengths to pass through said first slit system and through saidimage-bearing medium, means for applying signals representative of thecolor components of said televised objects to said means for deformingsaid medium, said deforming means thereupon being adapted to causefrequency and amplitude modulated deformations in said medium, thefrequencies of said modulated deformations being such as to permit onlycertain of said plurality of wavelengths of light to pass through saidsecond slit system onto said viewing surface, the amplitude of saidmodulated deformations being such as to control the amounts of saidcertain wavelengths which pass through said second slit system, saidlight passing second slit system in response to said amplitude andfrequency modulated deformations being adapted to produce colortelevision images on a viewing surface.

17. Apparatus for producing color television images, comprising firstand second slit systems, an image-bearing medium located between saidslit systems, means for transmitting light of a plurality of wavelengthsthrough said first slit system and through said medium, means fordeforming the surface of said medium, means for applying signalsrepresentative of selected color components of televised objects to saiddeforming means, said deforming means thereupon causing deformations insaid media um whose frequency is related to the hue of said colorcomponents, said deforming means being further adapted to modulate saiddeformations in amplitude, the amplitude of said modulations beingrelated to the intensity of said color components, said frequency ofsaid deformations causing said medium to form interference spectra onsaid second slit system so that said second slit system passessubstantially only light predetermined dominant wavelengths, saidamplitude modulations causing proportionate amounts of light of saidpredetermined dominant wavelengths to pass through said second slitsystem.

18. Color television projection apparatus, comprising first and secondslit systems, an image-bearing medium located between said slit systems,means for transmitting light of a plurality of wavelengths through saidfirst slit system and through said medium, means including deflectingmeans for deforming the surface of said medium, a plurality of means forproducing oscillatory waves having respectively different frequencies, aplurality of modulating means each coupled to a corresponding one ofsaid means for producing said oscillatory waves, means for applying eachof a plurality of voltage waves representative of selected colorcomponents of televised objects to a corresponding one of saidmodulating means, said modulating means thereupon being adapted toproduce output waves of a given frequency which are modulated inamplitude in response to one of said color representative voltage waves,means for combining said output waves, means for applying said combinedoutput waves to said means for deforming said medium, said mediumthereupon producing interference spectra, said interference spectrafalling upon said second slit system such that substantially only lightof predetermined dominant wavelengths passes through said second slitsystem, said dominant wavelengths being related to the colors of whichsaid voltage waves are representative, the amount of light of saidpredetermined dominant wavelengths passing through said second slitsystem being related to the intensity of said color representativevoltage waves.

19. A system for projecting color television images in response tosignals containing a plurality of voltage waves representative ofselected color components and representative of the luminance componentsof a televised object, comprising in combination first and second slitsystems, an essentially transparent conductive liquid positionedintermediate said first and second slit systems, means for modulatingsaid liquid in response to said luminance components whereby surfacedeformations of said liquid having amplitude variations correspondingthereto are produced, means for modulating said liquid whereby surfacedeformations having frequency and amplitude variations corresponding tosaid color components are produced, and means for passing light having aplurality of wavelengths through said first slit system and said liquid,said liquid thereupon being adapted to cause varying amounts of saidlight to pass through said second slit system as a function of theamplitude of the deformations in its surface corresponding to saidluminance components, said liquid being further adapted to cause lightof a restricted number of said plurality of wavelengths to pass saidsecond slit system as a function of the frequency of the deformations inits surface corresponding to said color components, said light passingsaid second slit system thereby producing a color television image on aviewing surface.

20. Color television projection apparatus comprising first and secondslit systems, an image bearing medium located between said first andsecond slit systems, means for transmitting light of a plurality of wavelengths through said first slit system and through said medium, meansfor deforming the surface of said medium, means for producingoscillatory waves having a plurality of different frequenciescorresponding to respective colors, means to modulate waves of each ofsaid frequencies, and to apply the modulated wave to said deformingmeans, a source of a plurality of voltage waves representative ofselected color components of televised objects, and means to apply eachof said voltage waves to said modulating means to modulate anoscillatory wave of frequency corresponding to the respective colorcomponent, said deforming means thereby causing deformations in saidmedium the frequencies of which correspond respectively to each of thefrequencies of said oscillatory waves, and the amplitude of which arerelated to each of said color representative voltage waves, said mediumthereupon causing different interference spectra to fall upon saidsecond slit system in response to light transmitted by said medium, saidspectra falling on said second slit system in such fashion thatsubstantially only light of different predetermined dominant wavelengths pass therethrough to form a color image of said televisedobjects.

References Cited in the file of this patent or the original patentUNITED STATES PATENTS 2,330,172 Rosen-thal Sept. 21, 1943 2,391,451Fischer Dec. 25, 1945 2,513,520 Rosenthal July 4, 1950 2,600,397 FischerJune 17, 1952 2,605,352 Fischer July 29, 1952 2,623,942 Schlesinger Dec.30, 1952 2,646,462 Sziklai July 21, 1953 2,681,380 Orthuber June 18,1954 2,723,305 Raibourn Nov. 8, 1955 2,740,829 Gretener Apr. 3, 19562,740,830 Gretener Apr. 3, 1956 2,740,833 Gretener Apr. 3, 1956 OTHERREFERENCES Wood: An Application of the Diffraction-Grating toColour-Photograph, London, Edinburgh, and Dublin Philosophical Magazineand Journal of Science, Fifth Series, vol. 47, Jam-June 1899, pages 368to 372. (Q1 P5 in Scientific Library-Patent Ofiice.)

